Crespi B, Badcock C. Psychosis and autism as diametrical disorders of the social brain. Behav Brain Sci 31: 241-261

Department of Biosciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
Behavioral and Brain Sciences (Impact Factor: 20.77). 06/2008; 31(3):241-61; discussion 261-320. DOI: 10.1017/S0140525X08004214
Source: PubMed


Autistic-spectrum conditions and psychotic-spectrum conditions (mainly schizophrenia, bipolar disorder, and major depression) represent two major suites of disorders of human cognition, affect, and behavior that involve altered development and function of the social brain. We describe evidence that a large set of phenotypic traits exhibit diametrically opposite phenotypes in autistic-spectrum versus psychotic-spectrum conditions, with a focus on schizophrenia. This suite of traits is inter-correlated, in that autism involves a general pattern of constrained overgrowth, whereas schizophrenia involves undergrowth. These disorders also exhibit diametric patterns for traits related to social brain development, including aspects of gaze, agency, social cognition, local versus global processing, language, and behavior. Social cognition is thus underdeveloped in autistic-spectrum conditions and hyper-developed on the psychotic spectrum.;>We propose and evaluate a novel hypothesis that may help to explain these diametric phenotypes: that the development of these two sets of conditions is mediated in part by alterations of genomic imprinting. Evidence regarding the genetic, physiological, neurological, and psychological underpinnings of psychotic-spectrum conditions supports the hypothesis that the etiologies of these conditions involve biases towards increased relative effects from imprinted genes with maternal expression, which engender a general pattern of undergrowth. By contrast, autistic-spectrum conditions appear to involve increased relative bias towards effects of paternally expressed genes, which mediate overgrowth. This hypothesis provides a simple yet comprehensive theory, grounded in evolutionary biology and genetics, for understanding the causes and phenotypes of autistic-spectrum and psychotic-spectrum conditions.

  • Source
    • "Both Hyper-and HypoToM can lead to errors on standard ToM tasks, but these different strategies would lead to different kinds of error (Frith, 2004). According to the diametric model of the mind and mental illness, all mental disorders can be located along this dimension of ToM ranging from Hypo-to HyperToM (Crespi & Badcock, 2008; Badcock, 2011). It has been hypothesized that individuals with ASD and individuals with psychosis spectrum disorders (PSD) may be located at the extreme ends (Ciaramidaro et al. 2015). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Knowledge on the risk mechanisms of psychotic experiences (PE) is still limited. The aim of this population-based study was to explore developmental markers of PE with a particular focus on the specificity of hyper-theory-of-mind (HyperToM) as correlate of PE as opposed to correlate of any mental disorder. Method: We assessed 1630 children from the Copenhagen Child Cohort 2000 regarding PE and HyperToM at the follow-up at 11-12 years. Mental disorders were diagnosed by clinical ratings based on standardized parent-, teacher- and self-reported psychopathology. Logistic regression analyses were performed to test the correlates of PE and HyperToM, and the specificity of correlates of PE v. correlates of any Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) mental disorder. Results: Univariate analyses showed the following correlates of PE: familial psychiatric liability; parental mental illness during early child development; change in family composition; low family income; regulatory problems in infancy; onset of puberty; bullying; concurrent mental disorder; and HyperToM. When estimating the adjusted effects, only low family income, concurrent mental disorder, bullying and HyperToM remained significantly associated with PE. Further analyses of the specificity of these correlates with regard to outcome revealed that HyperToM was the only variable specifically associated with PE without concurrent mental disorder. Finally, HyperToM did not share any of the investigated precursors with PE. Conclusions: HyperToM may have a specific role in the risk trajectories of PE, being specifically associated with PE in preadolescent children, independently of other family and child risk factors associated with PE and overall psychopathology at this age.
    Full-text · Article · Sep 2015 · Psychological Medicine
  • Source
    • "Interactions among conspecifics constitute an important basis for the organization of life and provide many health benefits to social species. Deficits in social behavior are linked to developmental abnormalities in children, such as autism spectrum disorders (ASD), and can also occur later in life as a sign of major psychiatric illnesses such as schizophrenia or major depression (Crespi and Badcock, 2008). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Social interactions in vertebrates are complex phenomena based on affective and cognitive processes. Multiple brain regions and neurotransmitter systems are involved in the expression of social behaviors, but their individual roles in specific aspects of social interactions are not well understood. Here we investigated how Gq-protein coupled metabotropic glutamate receptor 5 (mGluR5) and oxytocin receptor (Oxtr) affect social affiliation and social memory. We used conditional genetic approaches in which the genes coding for these receptors were knocked out in the lateral septum by infusion of recombinant adeno-associated viral vectors containing Cre recombinase (AAV-Cre). Social behavior was assessed two weeks later using a three-chamber paradigm for sociability and preference for social novelty. Septal deletion of mGluR5 abolished sociability while leaving preference for social novelty intact. In contrast, deletion of Oxtr did not affect sociability but significantly impaired preference for social novelty. Nonsocial behaviors or memories, including novel object recognition or fear conditioning, were not affected by these genetic manipulations. Immunohistochemical analyses of the distribution of mGluR5 and Oxtr revealed non-overlapping localization of these receptors within the lateral septum, suggesting that not only different neurotransmitters, but also different neuronal types contribute to sociability versus preference for social novelty. Our findings identify highly specialized roles of lateral septal mGluR5 and Oxtr in the the regulation of discrete social behaviors, and suggest that deficits in social interactions, which accompany many mental illnesses, would benefit from comprehensive treatments targeting different components of social functioning.Neuropsychopharmacology accepted article preview online, 31 March 2015. doi:10.1038/npp.2015.81.
    Full-text · Article · Mar 2015 · Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology
  • Source
    • "This could also help to establish the validity of the assumption that there is a continuum of social ability relating to the number and severity of autistic traits, regardless of a clinical threshold. Social difficulties such as problems in forming or maintaining interpersonal relationships or engaging in inappropriate behaviour are often central to the everyday struggles that individuals with ASD face (Troisi 2008; Crespi and Badcock 2008). In order to design effective interventions, such as social skill training, it is important to have a detailed understanding of how individuals' symptoms may interact with the environment and disrupt everyday functioning. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Measuring autistic traits in the general population has proven sensitive for examining cognition. The present study extended this to pro-social behaviour, investigating the influence of expectations to help others. A novel task describing characters in need of help was administered to students scoring high versus low on the Autism-Spectrum Quotient. Scenarios had two variants, describing either a 'clear-cut' or 'ambiguous' social rule. Participants with high versus low autistic traits were less pro-social and sympathetic overall towards the characters. The groups' ratings of char-acters' expectations were comparable, but those with high autistic traits provided more rule-based rationales in the clear-cut condition. This pattern of relatively intact knowledge in the context of reduced pro-social behaviour has implications for social skill training programmes.
    Full-text · Article · Feb 2015 · Journal of Autism and Developmental Disorders
Show more